Experimental validation of relationship between interrupting capacity of axial magnetic field vacuum interrupters with cup type contacts and their contact diameters and contact gaps

The relationship between maximum interrupting capacity of AMF vacuum interrupters with cup type contacts and their contact diameters and contact gaps is proposed to be I = k × D2 × Bz0.4, which is experimentally validated in this paper. The contact diameters of the prototype vacuum interrupters are 48, 58 and 66 mm and the contact gaps are 8, 11 and 14 mm separately. 9 vacuum interrupters are tested with oscillation circuit to measure their limit interrupting capacity. Axial magnetic flux density in the 9 cases is analyzed by 3D finite element method. With the calculated axial magnetic flux density results, limit interrupting capacity of the vacuum interrupters is predicted by the equation, which is compared with the experimental results and rated interrupting capacity. Considering experimental errors, the prediction results are meaningful.